This invention relates to fail-safe apparatus for producing a gas by chemical reaction of two or more compounds, at least one of which must be a liquid. It is particularly suited for the generation of corrosive or poisonous gases, such as chlorine, bromine chloride, hydrogen sulfide, and other gases, in view of the safety assured, but it is primarily directed toward the generation of chlorine. Normally these gases are stored in high pressure cylinders and are disposed using expensive equipment, which requires skilled operators and which is costly.
Chlorine has long been used as a sanitizer in applications such as pools, drinking water, and water cooling equipment. The least expensive system for sanitizing with chlorine involves the use of gaseous chlorine but this method suffers the disadvantages listed above.
Where an inexperienced person must apply chlorine, such as in a swimming pool treatment, it is safer to use liquid sodium hypochlorite or solid derivatives such as calcium hyochlorite or combinations of chlorine with cyanuric acid. The latter are by far the most expensive sources of chlorine, the least expensive being calcium hypochlorite, which unfortunately adds calcium salts to the water resulting in scale formation on the sides of the pool, especially in hard water areas, and the pool often must be drained and washed with acid to remove the scale. Liquid sodium hypochlorite is intermediate in cost, but it is very disadvantageous in that it can injure the hands and loses much of its strength on aging in hot weather. Consequently a pool may be unintentionally undertreated, resulting in algae formation. Another disadvantage in using these compounds is that they raise the pH, necessitating the addition of acid at intervals. All of these compounds leave residual salts in the water, which are undesirable.
To overcome these difficulties, applicant produces chlorine gas in a novel fail-safe generator by the reaction of an acid with calcium hypochlorite, the least expensive chlorine compound. Moreover, this compound is very stable and can be stored even in a hot climate for long periods without losing its strength. Using the apparatus described above, chlorine may be safely produced at low cost. Moreover, there is normally no need to add acid to the pool, as the pH stays within the proper range.